Winding-coil for dynamo-electric machines.



G. B. SKINNER.

- WINDING con, FOR DYNAMO ELECTRIC MACHINES.

APPLICATION FILED OCT. 7, 1908.

999,893; Patented Aug. 8,1911.

INYENTOR ATTO RN EY UNITED STATES PATENT orrIoE.

CHARLES E. SKINNER, OF 'WILKINSBURG, PENNSYLVANIA, ASSIGNOR, BY MESNEASSIGNMENTS, TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, OF EASTPITTSBURG, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

WINDING COIL FOR DYNAMIC-ELECTRIC MACHINES.

Specification or Letters Patent.

To all whom it may concern:

Be it known that I, CHARLES E. SKINNER, a citizen of the United States,and a resident of Wilkinsburg, in the county of Allegheny are oftenconstructed by winding copper strap or ribbon into arectangular helix,and since the voltage between turns in coils of this character isrelatively low, strips of insulating material have usually been insertedbetween the turns of the helix in preference to wrapping the conductorwith insulating tape or completely covering it by other means, in orderto improve the ventilation of the winding. I a

According to my present inventioml employ metallfoil or very thin metalribbon which has been so treated as to produce a hard film or coating ofinsulation on its surface. By this means, the space occupied by theinsulation so produced is relatively small, since foil'of approximatelyone-thousandth of an inch in thickness may be employed, and, in additionto this advantage, the coil is rendered fireproof and capable of operation at high temperatures.

It will be readily understood by .those' skilled in the art that theelectrical design of a coil to which the aforesaid insulation is to beapplied, may be so modified as to effect a material saving in. theamount of copper required. p

Figure of the accompanying drawing is a perspective view of a coilconstructed in accordance with my invention, and Figs. 2 and 3 aresectional elevations of the coil of Fig. 1 with insulating wrappings ofheat.- conducting material applied thereto. Fig. 4 is a sectionalelevation, on a larger .scale, of a portion of a coil disclosing amodified insulating structure embodying my invention.

Referring to the drawings, the coil here illustrated comprises aplurality of turns of conducting strap or ribbon, which, together,

constitute a substantially rectangular helix, the turns being wound onedge so that the flat surfaces of the ribbon are adjacent to each other.After the coil is formed of bare copper ribbon or strap, strips 2 ofmetal foil are interposed between the adjacent turns of the helix, saidstrips having first been treated to produce the insulating coating orfilm on their surfaces; ,The edges of the conducting strap of which thecoil is wound are insulated by a close wrapping 3 of metal foil, similarto that employed be-' tween the turns of the helix, the necessaryinsulation being obtained by treating the foil as hereinafter pointedout and by employing any desired number ofoverlapping turns. Thewrapping is bound 'as tightly as possible to the coil in order toimproveits eat-conducting properties by excluding films of air which, whenheated, become poor heat-conductors. For mechanical reasons, thethickness. of the foilor'plate used in the wrapping 3 may be increasedand the wrap ping built up ofoverlapping angle plates 4 arranged totelescope together, as shown in Fig, 3.

here the insulation is required to withstand relatively high voltages,sheets 5 of mica may be interposed between layers of the metal foil asshownin Fig. 4 of the drawings. 7

An insulating fabric constructed in the manner just referred to has theadvantage of being fireproof, while the aluminum foil holds the micaflakes in position.

I prefer toemploy strips of aluminum foil of substantiallyone-thousandth (1/ 1000) of an inch in thickness, in order that aminimum amount of space may be-occupied by the insulation and in orderthat the fireproof insulating film may readily be formed on its surface.A specially good result may be obtained by passing the strip of aluminumthrough a bath of ammonium bora-te or some other suitable liquid and atthe same time passing current through the electric conductor and thebath, thereby roducing an aluminum-oxid film which is 're latively hard,not readily destroyed byv heat, and at the same time affords adequateinsulation for a considerable voltage which is far in excess of thevoltage which usually obtains between adjacent turns of the field coilsof a dynamo-electric machine.

Patented Aug. 8, 1911.

It will be readily understood that my invention is not restricted to anyspecific type or kind of coil, and I desire that only such limitationsshall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A fireproof coil for electrical apparatuscomprising a plurality ofturnsof conductin material separated by metal foil treate to produce aninsulating coating or film on its surface.

2. A fireproof coil for electrical apparatus comprising a plurality ofturns of copper strap or ribbon and a suit-able strip or layer of metalfoil interposed between adjacent turns, said metal foil being firsttreated to provide an insulatin film on its surface.

3. A fireproof coi for electrical apparatus, comprising a plurality ofturns of confoil.

- In testimony whereof; I have hereunto subscribed my name this 21st-dayof Sept, 1908.

CHARLES E. SKINNER.

Witnesses:

LILIAN I. JOHN, BIRNEY HINES.

